Macbook Pro Maya 2008 problem

I'm running Maya 2008 on my Macbook Pro with GeForce 8600m gt graphics card. After about a week of use, my front viewport panel now displays blank gray. I have read on forums that there have been a lot of problems with using this graphics card to run Maya and driver downloads were suggested, but none apply to me since I am running it with os x. Anyone have any ideas? Thank you in advance for your help.